This invention relates in general to vehicle wheel hub and bearing retention systems and in particular to an improved structure for such a vehicle wheel hub and bearing retention system and method for producing the same.
One example of a known vehicle wheel hub and bearing retention system, indicated generally at 10, is illustrated in prior art FIG. 1. As shown therein, the prior art vehicle wheel hub and bearing retention system 10 is associated with a wheel (not shown) of a vehicle and includes a wheel hub 12 and a bearing unit 14. The wheel hub 12 defines a longitudinal axis X and includes a generally stepped body having in opened inboard end 16, an opened outboard end 18, and a generally axially extending main body 20 having a radially outwardly extending flange 22. The wheel hub 12 is provided with a bearing seat 24 for receiving the bearing unit 14.
The flange 22 of the wheel hub 12 has a plurality of circumferentially spaced lug bolt receiving holes 22A formed therein (only two of such lug bolt receiving holes 22A are illustrated in FIG. 1). A lug bolt 26 is disposed in each of the lug bolt receiving holes 22A to secure a brake rotor (not shown) and the vehicle wheel to the wheel hub 12 for rotation therewith. The outboard end 18 of the wheel hub 12 is adapted to receive a dust cover (not shown) to prevent dirt, mud, water, and other debris from entering into the interior of the wheel hub 12 through the opened outboard end 18.
The illustrated bearing unit 14 is a pregreased, sealed-for life, one-piece cartridge style bearing pack assembly and includes an outwardly extending flange 28. The flange 28 has a plurality of circumferentially spaced mounting bolt receiving holes 28A formed therein (only one of such mounting bolt receiving holes 28A is illustrated in FIG. 1). A mounting bolt (not shown) is disposed in each of the mounting bolt receiving holes 28A to secure the bearing unit 14 to a non-rotatable component of the vehicle, such as the steering knuckle (not shown), so as to rotatably support the wheel hub 12 relative thereto.
A spanner nut 30 is installed on the wheel hub 12 adjacent the opened inboard end 16 thereof to secure the bearing unit 14 on the wheel hub 12 and to preload the bearing unit 14. As shown in prior art FIG. 3, the spanner nut 30 is a generally annular shaped nut and includes an inner end wall 32, an outer end wall 34, an inner cylindrical side wall 36, and an outer cylindrical side wall 38. The outer end wall 34 of the spanner nut 30 defines an engagement surface which is oriented generally perpendicular to the longitudinal axis X of wheel hub 12. The engagement surface 34 is adapted to engage an inboard end surface 14A of the bearing unit 14 when the spanner nut 30 is installed and tightened on the wheel hub 12, as will be described below. The spanner nut 30 is preferably formed from stainless steel or carbon steel, and may be electroplated with zinc for corrosion protection. However, the spanner nut 30 can be formed from other materials, such as for example, aluminum.
As best shown in prior art FIG. 2, the spanner nut 30 is further provided a plurality of slots 40 (four slots 40 being illustrated in prior art FIG. 2) formed in the outer cylindrical side wall 38. The slots 40 extend from the inner end wall 32 to the outer end wall 34 of the spanner nut 30 and are adapted to allow a conventional tool (not shown) to be used to tighten the spanner nut 30 on the wheel hub 12. To accomplish this, the inner cylindrical side wall 36 of the spanner nut 30 is provided with internal threads 36A. The internal threads 36A of the spanner nut 30 mate with external threads 12A provided on the wheel hub 12 adjacent the inboard end 16 thereof. As is known, the spanner nut 30 is tightened against the inboard end surface 14A of the bearing unit 14 to a predetermined torque in order to exert a predetermined clamp load on the bearing unit 14.
The prior art vehicle wheel hub and bearing retention system 10 is subjected to various loads during vehicle operation. Typically, the loads which the prior art vehicle wheel hub and bearing retention system 10 are subjected to include radial loads, bending loads, and torsional loads. Depending on the magnitude of the associated loads and the rotational motion of the associated wheel hub 12 during vehicle operation, the spanner nut 30 can rotate and loosen from its installed position resulting in the loss of the preset bearing preload. Thus, it would be desirable to provide an improved structure for a vehicle wheel hub and bearing retention system which improves the retention of the bearing unit on the wheel hub in order to maintain a preset bearing preload and yet is simple and inexpensive.